Properly inflated tires are an important part of tire care. Properly inflated tires run cooler and more efficiently, which improves handling, extends tread life and tire life, and increases gas mileage. Vehicle and tire manufacturers typically provide information for proper air pressure for each vehicle tire. The pressures are known as placard pressures, and may be included in the vehicles owner's manual, and may also be on a sticker positioned on the vehicle. Placard pressures are usually given for “cold” tire conditions, such as 30 psi at 30° C. In addition, many times instruction is given to add 3 or 4 psi to the placard pressure if the tire is “warm”.
Tires normally lose about one to two pounds of pressure per month. Observant drivers are aware that vehicle environment affects tire pressure, and a conscientious driver will likely be able to determine whether a tire pressure change was caused by a seasonal adjustment (it goes down when the temperature drops and up when the temperature rises), requiring a top-off of pressure on all tires, or an air loss requiring full inspection of all tires.
In a study done by the Rubber Manufacturers Association (RMA) in 2004, only one person in seven correctly checks their car's tire pressure. In addition, the study also found that 30 percent of drivers wrongly believe that the best time to check their tires is when they are warm after being driven for at least a few miles and nearly ⅓ of drivers wrongly believe that if they are taking a trip with a fully loaded vehicle that they are better off if their tires are a little bit underinflated.
This type of information indicates that many drivers do not know when or if a tire is cold or warm, do not know what the proper pressure should be, and if the measured tire pressure does change, do not know if the pressure change was due to temperature change or loss of air from the tire.
Accordingly, it is desirable to provide a method for determining the cause of tire pressure change. In addition, it is desirable to communicate the type of attention required to resolve the tire pressure change. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.